FreeLists / si-list / [SI-LIST] Re: A question about data mask in SDRAM/DDR

[Wyland <dcwyland@xxxxxxxxxxxxx>]

I am not sure, but I think the DQM mask is for graphics. When you do a 
hardware based
graphic engine BITBLT move of a patch of pixels, you want to write part 
of a word at the
edges, so you inhibit the bits that do not get overwritten by the move. 
This is left over from
earlier DRAMs. However, I have not done any research to verify this. 
Comments, anyone?

Dave Wyland


Jack W.C. Lin wrote:

>Hi Dear All SI friend:
>In my rough memory, the purpose of data mask (DQM) in SDRAM is to avoid data
>contention when read change into write or write change intoe read. But in
>DDR, there is no need for DQM when data in read operation. Why? If my point
>is wrong, what is real role of DQM, is it similiar to byte enable? If there
>is someone familiar with this, please give me some comments, Thanks!
>Jack 
>
>
>------------------------------------------------------------------
>To unsubscribe from si-list:
>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
>or to administer your membership from a web page, go to:
>http://www.freelists.org/webpage/si-list
>
>For help:
>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>List archives are viewable at:     
>               http://www.freelists.org/archives/si-list
>or at our remote archives:
>               http://groups.yahoo.com/group/si-list/messages 
>Old (prior to June 6, 2001) list archives are viewable at:
>               http://www.qsl.net/wb6tpu
>  
>
>
>  
>



------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages 
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu